Right, you cannot say now "don't worry" after all this drama. I'm sorry. That's not how you deal with the community.
Furthermore, at this moment, please keep all information and process public so everyone that has similar issues, or wants to be updated on the matter, knows how to potentially fix it.
I've opened your latest zoo file - and like
@Cocolori I had no issues moving the lions to the quarantine building or the habitat.
Now, let's try this. I saved the same file with the lions in the habitat, and I've uploaded it to the workshop. Here's the link,
https://steamcommunity.com/sharedfiles/filedetails/?id=2508684221, it's called "Pride Rock Zoo Tobs". Could you please confirm whether you can open the file, and move the lions from their habitat to the quarantine building and or trade center?
We need to rule out whether it's something that your personal zoo file has or whether it's something intrinsic to your game.
But again, please keep all information public, so everyone can follow the story.